For detailed information about the amounts and types of (a) sex and nudity, (b) violence and gore, (c) profanity, (d) alcohol, drugs, and smoking, and (e) frightening and intense scenes in this movie, consult the IMDb Parents Guide for this movie. The Parents Guide for Halloween H20 can be found here.

Twenty years after her brother, Michael Myers, attempted to kill her on Halloween 1978, Laurie Strode (Jamie Lee Curtis) still experiences nightmares, flashbacks, and visions of Michael coming after her. Now the headmistress at Hillcrest Academy, a posh, private, gated high school in Summer Glen, Northern California, and living under the assumed name of Keri Tate, Laurie must face her evil brother one more time this Halloween 1998. This time, however, her fear is not only for herself but for her 17-year old son John (Josh Hartnett).

For two reasons. (1) Michael's body was never found after the events of the first two films, which would contradict 4, 5, and 6 where he was in a coma then clearly reappeared. (2) It does not make much sense as to why Laurie would leave behind her daughter Jamie after faking her death but keep her son John who, in the timeline. would be only a year younger than Jamie. A scene in the original treatment established that 4-6 were in continuity by having a student give a report on the "Haddonfield Murders", talking about Michael hunting and eventually killing Jamie after which Keri goes to the bathroom to throw up, but this never made it into the final movie. The 2009 comic 'Halloween: 30 Years of Terror' contends that the story in Halloween 4, 5, and 6 are comic stories written by Tommy Doyle, the boy who Laurie babysat in the first film and who is a lead protagonist in the sixth film. He has a son named Jamie, whose name was given to the character Jamie Lloyd. In the movie series, however, the only real tie is that, in H4, Laurie is said to have died, but it's now explained that she faked her death and went into hiding.

In the opening scenes of the movie, Michael (Chris Durand) ransacks the Illinois home of nurse Marion Chambers Whittington (Nancy Stephens), the same nurse who accompanied Dr Sam Loomis (Donald Pleasence) the night that Michael first escaped from Smith's Grove Sanitarium in 1978, and steals Laurie's files before killing Marion. Michael now knows where to find Laurie and begins the trek from Illinois to Northern California.

Halloween H20 ignores the events in H4, H5, and H6 and harkens back to the original series as presented in Halloween and Halloween II. Michael was 21 in those movies so, 20 years later, he is now 41 years old.

In the opening scenes, Nurse Marion Wittington is slashed across the neck, Jimmy Howell (Joseph Gordon-Levitt) is found with an ice skate through the face, and Jimmy's friend is stabbed in the back with a knife. Later in the movie, Charlie (Adam Hann-Byrd) is slashed across the neck, Sarah Wainthrope (Jodi Lyn O'Keefe) is stabbed in the back numerous times with a knife, and Doctor Will Brennan (Adam Arkin) is stabbed through the back with a knife.

As the paramedics load Michael's lifeless body into the coroner's truck, Laurie picks up the axe and jumps into the cab, not trusting that he's really dead. She drives off, heading down the highway. Michael begins to stir within the bodybag, eventually making his way free. Laurie slams on the brakes, and Michael goes flying through the window, landing in the road. When he begins to get up again, Laurie rams him with the truck and then drives off the cliff, sending them both plummeting down the hill. Laurie is thrown clear of the truck, but Michael is pinned against a tree limb. Taking the axe with her, Laurie approaches the dazed Michael. He reaches out his hand to her, and Laurie responds by reaching her hand out to him, touching his fingers. In the final scene, she swings the axe and beheads him.

Director Steve Miner, writers Robert Zappia and Matt Greenberg, and leading actress Jamie Lee Curtis commented on how they wanted the character of Laurie Strode to finally confront her worst fears and to face her brother one on one. H20 was supposed to end the Halloween movie saga. However, after the success of H20, it was stated that the Halloween series was expected to continue and that Jamie Lee Curtis was contractually obligated to film a cameo in a follow-up Halloween film. Consequently, Halloween: Resurrection came out four years later. If H20 had not done well at the box office, this may have been the last film (until Rob Zombie did his versions).

There are at least two more cuts going around of this movie. First of all there's a TV version that aired on the FX network in the States that features scenes not available in the Theatrical Version. In contrast they deleted most of the gore scenes and exchanged them with alternate material plus all curse words were edited. A detailed comparison between these versions can be found here.. Then there's a workprint in which a different score was used: the original Halloween theme. Of course there are also some minor changes, which can be found here.